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Updated: Sep 27, 2025

A New Single Chamber Implantable Defibrillator with Atrial Sensing: A Practical Demonstration of Sensing and Ease of Implantation
Published on: February 28, 2012
Inappropriately long post-ventricular atrial blanking leading to 'unnecessary' defibrillator discharge
Debabrata Bera1, Ayan Kar1, Arya Kamal Das2
1Department of Cardiology, RTIICS, Kolkata, India.
Abstract:
A 55-year-old lady with non-ischemic cardiomyopathy (NICM) was referred for multiple implantable cardioverter defibrillator (ICD) shocks. Stored electrograms (EGM) revealed atrial flutter (AFL) with A > V. Morphology match was good and RR-intervals were irregular. Despite all these, the dual-chamber-ICD (Abbott medical) classified this as ventricular tachycardia (VT-2) via V > A algorithm where it did not analyze morphology/stability and delivered therapy. Anti-tachycardia-pacing (ATP) was delivered which induced a true VT (rate in VF-zone) and immediate shock was delivered. It was hence appropriate but an 'unnecessary' shock. The offender was found to be an inappropriately programmed long post-ventricular atrial-blanking (PVAB) of 200 ms which led to undersensing of several atrial electrograms, falsely making V > A during a clear AFL.
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